//Serial Port Added 
//1st edit on Neil's Code
// hello.stepper.bipolar.44.full.c
//
// bipolar full stepping hello-world
//
// Neil Gershenfeld
// 11/21/12
//
// (c) Massachusetts Institute of Technology 2012
// This work may be reproduced, modified, distributed,
// performed, and displayed for any purpose. Copyright is
// retained and must be preserved. The work is provided
// as is; no warranty is provided, and users accept all 
// liability.
//

#include <avr/io.h> 
//this library have the commands used with AVR
#include <util/delay.h> 
// this library used in delay commands

#define output(directions,pin) (directions |= pin) 
// set port direction for output
#define set(port,pin) (port |= pin) 
// set port pin (value =1)
#define clear(port,pin) (port &= (~pin))
 // clear port pin (value =0)
#define pin_test(pins,pin) (pins & pin) 
// test for port pin
#define bit_test(byte,bit) (byte & (1 << bit)) 
// test for bit set




#define bridge_port PORTA // H-bridge port
#define bridge_direction DDRA // H-bridge direction
#define Ab (1 << PA0) 
// H-bridge output pins (setting them to be output)
#define Aa (1 << PA1) // "
#define Bb (1 << PA3) // "
#define Ba (1 << PA4) // "
#define on_delay() _delay_us(25) 
// PWM on time = 25 microseconds
#define off_delay() _delay_us(5) 
// PWM off time = 5 microseconds
#define PWM_count 100 // number of PWM cycles
#define step_count 20 // number of steps

static uint8_t count;
//making a variable called "count"

// A+ B+ PWM pulse
//
void pulse_ApBp() {
  clear(bridge_port, Ab); //disables Ab
  clear(bridge_port, Bb); //disables Bb
  set(bridge_port, Aa);   //enables Aa
  set(bridge_port, Ba);   //enables Ba
   for (count = 0; count < PWM_count; ++count) {
      set(bridge_port, Aa); //enables Aa
      set(bridge_port, Ba); //enables Ba
      on_delay();     
      //PWM on time (Previously defined)
      clear(bridge_port, Aa); 
      //disables Aa in the end of the pulse
      clear(bridge_port, Ba); 
      //disables Ba in the end of the pulse
      off_delay();    
      //PWM off time (previously defined)
      }
   }
//
// A+ B- PWM pulse
//
void pulse_ApBm() {
  clear(bridge_port, Ab); //disables Ab
  clear(bridge_port, Ba); //disables Ba
  set(bridge_port, Aa);
  set(bridge_port, Bb);
   for (count = 0; count < PWM_count; ++count) {
      set(bridge_port, Aa);
      set(bridge_port, Bb);
      on_delay();
      clear(bridge_port, Aa); //disables Aa
      clear(bridge_port, Bb); //disables Aa
      off_delay();
      }
   }
//
// A- B+ PWM pulse
//
void pulse_AmBp() {
  clear(bridge_port, Aa); //disables Aa
  clear(bridge_port, Bb); //disables Aa
  set(bridge_port, Ab);  //enables Ab
  set(bridge_port, Ba);  //enables Ba
   for (count = 0; count < PWM_count; ++count) {
      set(bridge_port, Ab);
      set(bridge_port, Ba);
      on_delay();
      clear(bridge_port, Ab); 
      //disables Aa in the end of the pulse
      clear(bridge_port, Ba); 
      //disables Ba in the end of the pulse
      off_delay();
      }
   }
//
// A- B- PWM pulse
//
void pulse_AmBm() {
  clear(bridge_port, Aa); //disables Aa
  clear(bridge_port, Ba); //disables Ba
  set(bridge_port, Ab);   //enables Ab
  set(bridge_port, Bb);   //enables Bb
   for (count = 0; count < PWM_count; ++count) {
      set(bridge_port, Ab);
      set(bridge_port, Bb);
      on_delay();
      clear(bridge_port, Ab); 
      //disables Aa in the end of the pulse
      clear(bridge_port, Bb); 
      //disables Aa in the end of the pulse
      off_delay();
      }
   }
//
// clockwise step
// by this sequence of pulses we will get a step in clockwise direction
void step_cw() {
   pulse_ApBp();
   pulse_AmBp();
   pulse_AmBm();
   pulse_ApBm();
   }
//
// counter-clockwise step
// by this sequence of pulses we will get a step in anti clockwise direction
void step_ccw() {
   pulse_ApBm();
   pulse_AmBm();
   pulse_AmBp();
   pulse_ApBp();
   }

int main(void) {
   //
   // main
   //defining variables
   static uint8_t i,j;
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   // initialize bridge pins (by disabling all the H-bridge ports and setting their values = 0 )
   //
   clear(bridge_port, Aa);
   output(bridge_direction, Aa);
   clear(bridge_port, Ab);
   output(bridge_direction, Ab);
   clear(bridge_port, Ba);
   output(bridge_direction, Ba);
   clear(bridge_port, Bb);
   output(bridge_direction, Bb);
   //
   // main loop
   //
   while (1) {
      for (i = 0; i < step_count; ++i) {
         for (j = 0; j < i; ++j)
            step_cw();
         for (j = 0; j < i; ++j)
            step_ccw();
         }
      for (i = step_count; i > 0; --i) {
         for (j = 0; j < i; ++j)
            step_cw();
         for (j = 0; j < i; ++j)
            step_ccw();
         }
      }
   }